1) Field of the Invention
This invention relates generally to a device and method for e-beam curing films and more particularly a device and method for e-beam curing films such as low-k films or photoresist films in semiconductor devices.
2) Description of the Prior Art
Integrated circuit geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two year/half-size rule (often called Moore's Law), which means that the number of devices on a chip doubles every two years. Today's fabrication facilities are routinely producing devices having 0.13 μm and even 0.1 μm feature sizes, and tomorrow's facilities soon will be producing devices having even smaller feature sizes.
The continued reduction in device geometries has generated a demand for films having lower k values because the capacitive coupling between adjacent metal lines must be reduced to further reduce the size of devices on integrated circuits. In particular, insulators having low dielectric constants (k), less than about 4.0, are desirable. Examples of insulators having low dielectric constants include spin-on glass, un-doped silicon glass (USG), fluorine-doped silicon glass (FSG), and polytetrafluoroethylene (PTFE), which are all commercially available.
In order to minimize the RC delay, organic porous low-k materials are recommended to use as dielectric materials for BEOL interconnect for 65 nm technology and below. One big challenge for organic porous low-k film development is how to improve the mechanical strength while still maintaining low dielectric constant of organic porous films. An effective method to reduce the k value is to introduce pores into the film. As a result, low k films often exhibit poor mechanical strength (e.g., hardness), which may hinder the integration of the films into the manufacture of the device. Plasma post treatment is currently being used to increase mechanical strength of low k films. However, plasma treatment often causes the k value to increase.
A need, therefore, exists for a method for increasing the mechanical strength of low k films without having to increase the k value.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering the following.
US20040137760A1: Thin film processing method and system—Inventor: Onishi, Tadashi;—Thin film processing method in chemical vapor deposition apparatus, involves independently controlling output power and time of electron beam irradiated on wafer according to thickness distribution of film on wafer—Assignee: TOKYO ELECTRON LIMITED, Tokyo, Japan.
U.S. Pat. No. 5,989,983: Method of fabricating and curing spin-on-glass layers by electron beam irradiation—SOG layer curing method for use during manufacture of semiconductor device—involves irradiating electron beam at predefined temperature for specific time onto target plate formed with SOG layer—Inventor: Goo, Ju-seon;
US20040137758A1: Inventor: Li, Lihua—METHOD FOR CURING LOW DIELECTRIC CONSTANT FILM USING DIRECT CURRENT BIAS—Depositing low dielectric constant film on substrate for fabrication of integrated circuit by applying direct current bias to at least one of substrate or gas distribution plate to cure low dielectric constant film.
U.S. Pat. No. 6,607,991: Livesay et al. Method for curing spin-on dielectric films utilizing electron beam radiation—Spin-on dielectric material layer modification for semiconductor device, involves irradiating dielectric layer simultaneously with large area electron beam and heat until sufficient electron dose is accumulated.
US20030232495A1: Moghadam et al.—Methods and apparatus for E-beam treatment used to fabricate integrated circuit devices—Deposition of low dielectric constant film on substrate comprises depositing film comprising silicon, carbon, oxygen and hydrogen in chemical vapor deposition chamber, and exposing film to electron beam to increase its hardness.
U.S. Pat. No. 6,703,302: Inventor: Miyajima, Hideshi;—Method of making a low dielectric insulation layer—Fabrication of semiconductor device by heating silicon-containing low dielectric constant insulating film while irradiating with electron beam, and exposing the film to gas which promotes bond formation of silicon atoms.
U.S. Pat. No. 6,613,666—Ma, Shawming—Method of reducing plasma charging damage during dielectric etch process for dual damascene interconnect structures—Reduction of plasma-induced charging damage during etching of trench in dielectric layer by applying protective layer of conductive material on electrical contact opening and etching trench overlying electrical contact opening
US20040101632A1: Inventor: Zhu, Wen H.;—method for curing low dielectric constant film by electron beam—Deposition of low dielectric constant film on substrate comprises depositing film comprising silicon, carbon, oxygen and hydrogen in chemical vapor deposition chamber, and exposing film to electron beam to increase its hardness.